1. Field of the Invention
The present invention relates to an image formation apparatus. More particularly, the invention relates to an image formation apparatus preferably suitable for use of an ink jet recording method. Here, in this respect, recording includes the application of ink (printing) or the like for all the ink supporting members to receive it, such as cloths, threads, papers, sheet materials. The recording apparatus includes every kind of information processing apparatus or printer serving as the output equipment thereof. The present invention is applicable to recording by use of such apparatuses.
2. Related Background Art
The ink jet recording method is to cause droplets of recording liquid to fly and apply them to paper or other recording media for recording.
Generally, however, the main component of ink used for the conventional ink jet recording is water. It also contains water soluble high-boiling point solvents, such as glycol, to prevent ink from being dried or clogging of discharge ports, among other purposes. Therefore, when recording is performed on an ordinary paper using such ink, a sufficient fixation is not obtainable in some cases, and uniform images are not formed sometimes, either, presumably due to uneven distribution of loading material and sizing agent on the surface of a recording paper. Particularly when it is attempted to form color images, colors often spread on the boundaries of images of different colors or mixed unevenly because ink of plural kinds of colors are superposed one after another before each of them is fixed on the paper, thus making the provision of satisfactory images impossible.
Therefore, with a view to solving such problems, there is proposed a method, in which before recording ink is discharged, liquid is applied to a recording medium as a processing liquid that makes a good formation of images possible.
For example, a method is disclosed in Japanese Patent Laid-Open Application No. 5-202328, wherein there are used an ink component containing at least chemical dyeing agent having at least one carboxyl group, and a polyvalent metallic salt solvent, and then, the ink component is used to obtain good images on a recording medium subsequent to having applied the polyvalent metallic salt to the recording medium.
Also, in Japanese Patent Laid-Open Application No. 61-75870, there are disclosed an image formation method, a processing liquid, and an ink component used therefor in order to obtain images in good condition.
Then, a method is disclosed in the embodiments of patents filed with the Japanese Patent Laid-Open Application Nos. 5-202328 and 61-75870 to apply the processing liquid to a recording medium by use of a roller before recording is performed by use of an ink jet recording head.
Both of the method and technique thus disclosed are to use an application roller having a length more than the width of a recording medium for the application of the processing liquid to the recording medium in its width direction at a time.
In this method, that is, an application roller having a length more than the width of a recording medium is used for applying the processing liquid in the width direction of the recording medium at a time, the application roller is interlocked with the feeding operation of the recording medium to carry out an overall application of the processing liquid. As a result, although this method is effective, there are still encountered the problems given below.
(1) The application of processing liquid is performed even when a recording medium is not pinched by a pair of rollers. Therefore, the processing liquid is carried on all over the rollers, and when the recording medium is pinched by the rollers, the processing liquid is also applied around to the backside of the recording medium. Hence, not only the processing liquid is used wastefully, but also, it is transferred again to the platen, causing stains together with ink mist.
(2) The location where the processing liquid is applied and the portion where the image data are actually recorded by use of ink are physically apart from each other. As a result, it takes time before the image data are recorded after the processing liquid has been applied. Therefore, the processing liquid is caused to be overly permeated or volatilized, and the degradation of image quality ensues depending on the conformity of the processing liquid and ink containing coloring materials.
(3) When an image is formed by use of ink discharged from a recording head on a jointed portion of processing liquid on the surface of the recording medium (paper), the elapsed time becomes different since the processing liquid has been applied to the locations before and after such joint portion thereof. Therefore, despite ink is discharged simultaneously on the recording medium in the locations before and after such jointed portion, the degrees of permeation of the processing liquid differ before and after the jointed portion on the recording medium. As a result, there occurs difference in the surface density of the effective components that cohere the coloring materials contained in ink on the surface of the recording medium, thus causing the degrees of cohesion of such materials to vary. Consequently, unevenness is brought about in the images to be formed.
(4) The length of the roller should be made more than the width of a recording medium. This presents itself one factor that may hinder making the apparatus smaller.
Also, there are the following problems encountered in using the method, in which the processing liquid is being applied to a recording medium continuously by means of roller or the like that is in contact with the recording medium:
(1) If the processing liquid is applied, preceding ink discharges, to an OHP sheet or the so-called coated paper, that is, a recording medium having an ink receiving layer already formed on its base material, the recorded image is often degraded due to the influence of excessive amount of processing liquid because such medium is prepared in anticipation of the event that ink is directly impacted on the aforesaid ink receiving layer.
(2) When idle rotation is performed to feed or exhaust a recording medium, an excessive amount of processing liquid is applied to the platen unit arranged below the processing liquid application unit, when the processing liquid is applied by use of this unit without presence of any recording medium. As a result, the platen is stained by the adhesion of ink mist, and then, such stain is transferred again to the processing liquid application unit, thus inviting the adhesion of stains to the recording medium or the volume of processing liquid becomes short of the amount good enough to be applied to the anticipated sheet numbers of recording medium.
(3) The apparatus is used as a printer output of a computer or the like, and particularly when a large quantity of data should be transferred for the formation of highly precise color images, for example, there often occurs an interruption of image formation for a long time despite it is still in process because of such data transfer from the computer. Then, if means for applying processing liquid is left intact during such period of interruption, the processing liquid is applied to the recording medium more than necessary to cause the recorded image to be disturbed.
(4) When any defective feed of a recording medium such as the so-called jamming takes place, it is difficult to remove the recording medium if means for applying processing liquid should be left in contact with the recording medium, and the processing liquid is applied wastefully eventually.
Also, the method, in which a processing liquid retainer is provided separately from a recording ink retainer for the intended use, the problems are encountered with respect to refilling the processing liquid as given below.
In other words, even if recorded images become degraded due to the short supply of processing liquid, it is often difficult for the operator to grasp such cause of quality degradation, depending on the contents of the recorded images, because the processing liquid is essentially colorless and transparent in many cases. To enable him to know such causes brought about by the shortage of processing liquid, there is a need for the provision of independent means dedicated to serving such purpose for sensing the remains of processing liquid. The provision of a means of the kind naturally hinders making the apparatus smaller and its operation simpler to let the operator understand it easily.
The present invention is designed to solve the problems described above. It is an object of the invention to provide an image formation apparatus capable of obtaining high quality images with an enhanced formation process of inked images adhering to a recording medium to which processing liquid has been applied.
It is another object of the invention to provide an image formation apparatus having application means for applying processing liquid, while keeping such means in contact with a recording medium, the apparatus being arranged to apply the processing liquid only in a required quantity efficiently, and also, to avoid any hindrance that may result in making the apparatus smaller.
It is still another object of the invention to provide an image formation method and an apparatus using such method to make it possible to apply processing liquid in an appropriate quantity as required.
It is a further object of the invention to provide an image formation apparatus capable of obtaining uniform quality of recorded images without any unevenness in them by preventing the jointed portion of applied processing liquid from being placed on the area for an image to be recorded on the surface of a recording medium even when the degrees of permeation of processing liquid differ on the recording medium due to the difference in the elapsed time since the processing liquid has been applied to the locations before and after such jointed portion of the applied processing liquid on the surface of the recording medium, thus making the surface density of the effective components evenly formed for cohering the coloring materials in ink on the recording medium, as well as for regulating the degrees of the cohesion of coloring materials.
It is still a further object of the invention to provide an image formation apparatus capable of obtaining uniform images without any unevenness in them by preventing the jointed portion of processing liquid from being placed on the area of an image to be recorded on the surface of a recording medium even when the difference takes place in the surface density of the processing liquid due to the difference in the elapsed time since the processing liquid has been applied to the locations before and after such jointed portion of the applied processing liquid, thus making the surface density of effective components evenly formed for cohering the coloring materials in ink on the recording medium, as well as for regulating the degrees of the cohesion of the coloring materials.
It is another object of the invention to provide an image formation apparatus capable of securing processing liquid in a quantity sufficient enough at all the time so as to prevent the quality of recorded images from being degraded.
It is still another object of the invention to provide an image formation apparatus, including a carriage for moving an ink jet recording head relatively with respect to a recording medium to discharge ink containing coloring materials from the ink discharge ports; processing liquid application means for applying to the recording medium the processing liquid that coheres the coloring materials in ink, this processing liquid application means being arranged to be in contact with the recording medium and apply the processing liquid to the recording medium before ink to be discharged from the recording head of the ink jet recording head; here, the processing liquid application means being mounted on the aforesaid carriage.
It is still another object of the invention to provide an image formation apparatus that forms images on a recording medium by discharging ink containing coloring materials onto the recording medium, including processing liquid application means for applying the processing liquid that coheres the coloring materials in ink to a recording medium, while being in contact therewith before the ink is discharged onto the recording medium; and means for switching over modes for selectively setting the recording medium and processing liquid application means to be in contact with or apart from each other.
It is an object of the invention to provide a method for forming images using processing liquid application means for applying the processing liquid that coheres the coloring materials in ink to a recording medium, while being in contact therewith, before the ink is discharged onto the recording medium, including the step of selectively setting the recording medium and processing liquid application means to be in contact with or apart from each other.
It is another object of the invention to provide an image formation apparatus using an ink jet recording head for recording by discharging ink from the discharge ports onto a recording medium, including processing liquid supply means for supplying the processing liquid that coheres the coloring materials in ink; processing liquid application means for applying the processing liquid to an area of the recording medium before images to be recorded on it, here, the distance between the discharge port of the discharge port array on the uppermost stream side in the feeding direction of the recording medium, and the application point of the processing liquid application means to the recording medium being set at integral times the feeding pitch of the recording medium.
It is still another object of the invention to provide an image formation apparatus using an ink jet recording head for recording by discharging ink from the discharge ports onto a recording medium, including processing liquid supply means for supplying the processing liquid that coheres the coloring materials in ink; processing liquid application means for applying the processing liquid to an area of the recording medium before images to be recorded on it; recording medium feeding means capable of setting the feeding pitch of the recording medium at plural steps, here the distance between the discharge port of the discharge port array on the uppermost stream side in the feeding direction of the recording medium, and the application point of the processing liquid application means to the recording medium being set at integral times at least one feeding pitch of the plural feeding pitches of the recording medium.
It is still another object of the invention to provide an image formation apparatus using an ink jet recording head for recording by discharging ink from the discharge ports onto a recording medium, including processing liquid supply means for supplying the processing liquid that coheres the coloring materials in ink; processing liquid application means for applying the processing liquid to an area of the recording medium before images to be recorded on it; and processing liquid carrier means for carrying the processing liquid to the application point of processing liquid application means on the recording medium, here the distance for the processing liquid to be carried being set at integral times the feeding pitch of the recording medium.
It is still another object of the invention to provide an image formation apparatus using an ink jet recording head for recording by discharging ink from the discharge ports onto a recording medium, including processing liquid supply means for supplying the processing liquid that coheres the coloring materials in ink; processing liquid application means for applying the processing liquid to an area of the recording medium before images to be recorded on it; processing liquid carrier means for carrying the processing liquid to the application point of the processing liquid application means on the recording medium; and recording medium feeding means capable of setting the feeding pitch of the recording medium at plural steps, here the distance for the processing liquid to be carried being set at integral times at least one feeding pitch of the plural feeding pitches of the recording medium.
It is another object of the invention to provide an image formation apparatus using an ink jet recording head for recording by discharging ink from the discharge ports onto a recording medium, including processing liquid supply means for supplying the processing liquid that coheres the coloring materials in ink; processing liquid application means for applying the processing liquid to an area of the recording medium before images to be recorded on it while being rotatively in contact with such area, here the rotational direction of the processing liquid application means being opposite to the feeding direction of the recording medium.